Vaccine composition

ABSTRACT

There is described a kit for use in inducing an immune response in a mammal, the kit includes: a first virus that expresses MAGEA3, Human Papilloma Virus E6/E7 fusion protein, human Six-Transmembrane Epithelial Antigen of the Prostate protein, or Cancer Testis Antigen 1, or a variant thereof as an antigenic protein and that is formulated to generate an immunity to the protein or variant thereof in the mammal. The kit also includes a Maraba MG1 virus encoding the same antigen, or a variant of the same antigen. The Maraba MG1 virus is formulated to induce the immune response in the mammal. The first virus is immunologically distinct from the Maraba MG1 virus.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 14/769,035, filed on Aug. 19, 2015, which is a U.S. National Stage Entry of PCT Patent Application No. PCT/CA2014/050118, filed Feb. 20, 2014, which claims the benefit of and priority to U.S. Provisional Patent Application No. 61/767,776 filed Feb. 21, 2013, all of which are hereby incorporated by reference in their entirety for all purposes.

FIELD

The present disclosure relates to oncolytic viruses for inducing an immune response.

BACKGROUND

Oncolytic viruses (OVs) specifically infect, replicate in and kill malignant cells, leaving normal tissues unaffected. Several OVs have reached advanced stages of clinical evaluation for the treatment of various neoplasms (Russell S J. et al., (2012) Nat Biotechnol 30:658-670). Once approved, such viral agents could substitute or combine with standard cancer therapies and allow for reduced toxicity and improved therapeutic efficacy.

In addition to the vesicular stomatitis virus (VSV) (Stojdl D F. et al., (2000) Nat Med 6:821-825; Stojdl D F. et al., (2003) Cancer Cell 4:263-275), other rhabdoviruses displaying oncolytic activity have been described recently (Brun J. et al., (2010) Mol Ther 18: 1440-1449; Mahoney D J. et al., (2011) Cancer Cell 20:443-456). Among them, the non-VSV Maraba virus showed the broadest oncotropism in vitro (WO 2009/016433). A mutant Maraba virus with improved tumor selectivity and reduced virulence in normal cells was engineered. The attenuated strain is a double mutant strain containing both G protein (Q242R) and M protein (L123W) mutations. In vivo, this attenuated strain, called MG1 or Maraba MG1, demonstrated potent anti-tumor activity in xenograft and syngeneic tumor models in mice, with superior therapeutic efficacy than the attenuated VSV, VSV.6M51 (WO 2011/070440).

Data accumulated over the past several years has revealed that anti-tumor efficacy of oncolytic viruses not only depends on their direct oncolysis but may also depend on their ability to stimulate anti-tumor immunity (Bridle S W. et al., (2010) Mol Ther 184:4269-4275). This immune-mediated tumor control seems to play a critical role in the overall efficacy of OV therapy. Indeed, tumor-specific adaptive immune cells can patrol the tissues and destroy tumor cells that have been missed by the OV. Moreover, their memory compartment can prevent tumor recurrence.

Various strategies have been developed to improve OV-induced anti-tumor immunity (Pol J. et al., (2012) Virus Adaptation and Treatment 4:1-21). Some groups have genetically engineered OV expressing immunomostimulatory cytokines. A herpes simplex and a vaccinia virus expressing Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF) have respectively reached phase III and IIB of the clinical evaluation for cancer therapy while a VSV expressing IFN-β has just entered phase I.

Another strategy, defined as an oncolytic vaccine, consists of expressing a tumor antigen from the OV (Russell S J. et al., (2012) Nat Biotechnol 30:658-670). Previously, it has been demonstrated that VSV could also be used as a cancer vaccine vector (Bridle B W. et al., (2010) Mol Ther 184:4269-4275). When applied in a heterologous prime-boost setting to treat a murine melanoma model, a VSV-human dopachrome tautomerase (hDCT) oncolytic vaccine not only induced an increased tumor-specific immunity to DCT but also a concomitant reduction in antiviral adaptive immunity. As a result, the therapeutic efficacy was dramatically improved with an increase of both median and tong term survivals (WO 2010/105347). Although VSV was shown to be effective using hDCT as a tumor associated antigen, there is no way to predict what tumor associated antigens will be effective in a heterologous prime-boost setting.

It is desirable to provide a vaccine vector that can be used to activate the patient's immune system to kill tumor cells with reduced toxicity to normal tissues, for example by activating antibodies and/or lymphocytes against a tumor associated antigen on the tumor. It is desirable if such a vaccine vector displays both oncolytic activity and an ability to boost adaptive cell immunity.

SUMMARY

The following summary is intended to introduce the reader to one or more inventions described herein but not to define any one of them.

It is an object of the present disclosure to obviate or mitigate at least one disadvantage of previous anti-cancer vaccines.

The authors of the present disclosure have surprisingly determined that MAGEA3, Human Papilloma Virus E6/E7 fusion protein, human Six-Transmembrane Epithelial Antigen of the Prostate protein, and Cancer Testis Antigen 1, are all able to be used in a heterologous prime-boost setting to induce an immune response in a mammal. These results are unexpected and not predictable since not all tumor associated antigens are able to induce an immune response via a heterologous prime-boost. For example, the authors of the present disclosure also determined that Placenta-specific protein 1 (PLAC-1) and Epstein-Barr Nuclear Antigen 1 were unable to stimulate an immune response via a heterologous prime-boost.

In a first aspect, there is provided a kit for use in inducing an immune response in a mammal. The kit includes: a first virus that expresses a protein comprising an amino acid sequence of SEQ ID NO: 1, or a variant thereof, as an antigenic protein and that is formulated to generate an immunity to the protein or variant thereof in the mammal. The kit also includes a Maraba MG1 virus encoding a protein comprising an amino acid sequence SEQ ID NO: 1, or a variant thereof, as an antigenic protein, the Maraba MG1 virus formulated to induce the immune response in the mammal; the first virus being immunologically distinct from the Maraba MG1 virus. The antigenic protein expressed by the first virus and the antigenic protein expressed by the Maraba MG1 virus may be identical.

The first virus, the Maraba MG1 virus, or both, may be formulated for administration as isolated viruses.

The Maraba MG1 virus may include a reverse complement and RNA version of a transgene comprising a nucleotide sequence of SEQ ID NO: 2. The Maraba MG1 virus may include a reverse complement and RNA version of a codon optimized transgene comprising a nucleotide sequence of SEQ ID NO: 3.

The first virus may include a transgene comprising a nucleotide sequence of SEQ ID NO: 2 or 3, or may include a reverse complement and RNA version of a transgene comprising a nucleotide sequence of SEQ ID NO: 2 or 3, depending on whether the first virus is a positive sense RNA virus, a DNA virus, or a negative sense RNA virus.

The two viruses may be capable of expressing different variants of the protein that comprises the sequence of SEQ ID NO: 1. The variant of the protein comprising an amino acid sequence of SEQ ID NO: 1 that is expressed by the first virus, the Maraba MG1 virus, or both, may include at least one tumor associated epitope selected from the group consisting of: FLWGPRALV (SEQ ID NO: 27), KVAELVHFL (SEQ ID NO: 28), EGDCAPEEK (SEQ ID NO: 35), KKLLTQHFVQENYLEY (SEQ ID NO: 36), and RKVAELVHFLLLKYR (SEQ ID NO: 37), and be at least 70% identical to SEQ ID NO: 1. Preferably, the variant will be at least 80% identical to SEQ ID NO: 1. More preferably, the variant will be at least 90% identical to SEQ ID NO: 1. Even more preferably, the variant will be at least 95% identical to SEQ ID NO: 1.

The variant of the protein comprising an amino acid sequence of SEQ ID NO: 1 that is expressed by the first virus, the Maraba MG1 virus, or both, may have an amino acid sequence of SEQ ID NO: 4. The nucleotide sequence that encodes the variant may include a nucleotide sequence of SEQ ID NO: 5.

The Maraba MG1 virus may include a reverse complement and RNA version of a nucleotide sequence of SEQ ID NO: 5. The first virus may include a transgene comprising a nucleotide sequence of SEQ ID NO: 5, or may include a reverse complement and RNA version of a transgene comprising a nucleotide sequence of SEQ ID NO: 5, depending on whether the first virus is a positive sense RNA virus, a DNA virus, or a negative sense RNA virus.

If the first virus is a negative sense RNA virus, one of either the Maraba MG1 virus or the first virus may include a reverse complement and RNA version of a nucleotide sequence of SEQ ID NO: 2 or 3, and the other of the Maraba MG1 virus and the first virus may include a reverse complement and RNA version of SEQ ID NO: 5.

If the first virus is a positive sense RNA virus or a DNA virus, the Maraba MG1 virus may include a reverse complement and RNA version of a nucleotide sequence of SEQ ID NO: 2 or 3, and the first virus may include a nucleotide sequence of SEQ ID NO: 5. Alternatively, the Maraba MG1 virus may include a reverse complement and RNA version of a nucleotide sequence of SEQ ID NO: 5, and the first virus may include a nucleotide sequence of SEQ ID NO: 2 or 3.

One of either the Maraba MG1 virus or the first virus may be capable of expressing a protein that comprises the sequence of SEQ ID NO: 1 or 4, and the other of the Maraba MG1 virus and the first virus may be capable of expressing a protein that comprises the other sequence.

The first virus may be an adenovirus.

According to another aspect, there is provided an isolated Maraba MG1 viral particle having a genome that encodes a protein comprising an amino acid sequence of SEQ ID NO: 1, or a variant thereof.

The variant of the protein comprising an amino acid sequence of SEQ ID NO: 1 may have an amino acid sequence of SEQ ID NO: 4.

The genome may include a reverse complement and RNA version of a nucleotide sequence of SEQ ID NO: 2 or 3.

The genome may include a reverse complement and RNA version of a nucleotide sequence of SEQ ID NO: 5.

The genome may include a reverse complement and RNA version of a nucleotide sequence of SEQ ID NO: 6.

In another aspect, there is provided a kit for use in inducing an immune response in a mammal. The kit includes: a first virus that expresses a protein comprising an amino acid sequence of SEQ ID NO: 7, or a variant thereof, as an antigenic protein and that is formulated to generate an immunity to the protein or variant thereof in the mammal. The kit also includes a Maraba MG1 virus encoding a protein comprising an amino acid sequence of SEQ ID NO: 7, or a variant thereof, as an antigenic protein, the Maraba MG1 virus formulated to induce the immune response in the mammal; the first virus being immunologically distinct from the Maraba MG1 virus. The antigenic protein expressed by the first virus and the antigenic protein expressed by the Maraba MG1 virus may be identical.

The first virus, the Maraba MG1 virus, or both, may be formulated for administration as isolated viruses.

If the first virus is a negative sense RNA virus, the Maraba MG1 virus, the first virus, or both may include a reverse complement and RNA version of a codon optimized transgene comprising a nucleotide sequence of SEQ ID NO: 8. If the first virus is a DNA virus or a positive sense RNA virus, the first virus may include a codon optimized transgene comprising a nucleotide sequence of SEQ ID NO: 8.

The variant of the protein comprising an amino acid sequence of SEQ ID NO: 7 that is expressed by the first virus, the Maraba MG1 virus, or both, may include at least one tumor associated epitope and be at least 70% identical to SEQ ID NO: 7. Preferably, the variant will be at least 80% identical to SEQ ID NO: 7. More preferably, the variant will be at least 90% identical to SEQ ID NO: 7. Even more preferably, the variant will be at least 95% identical to SEQ ID NO: 7.

One of either the Maraba MG1 virus or the first virus may be capable of expressing a protein that comprises the sequence of SEQ ID NO: 7, and the other of the Maraba MG1 virus and the first virus may be capable of expressing a variant of a protein that comprises the sequence of SEQ ID NO: 7. The two viruses may be capable of expressing different variants of the protein that comprises the sequence of SEQ ID NO: 7.

The first virus may be a lentivirus.

According to another aspect, there is provided an isolated Maraba MG1 viral particle having a genome that encodes a protein comprising an amino acid sequence of SEQ ID NO: 7, or a variant thereof.

The genome may include a reverse complement and RNA version of a nucleotide sequence of SEQ ID NO: 8.

The genome may include a nucleotide sequence that is the reverse complement and RNA version of SEQ ID NO: 9.

In another aspect, there is provided a kit for use in inducing an immune response in a mammal. The kit includes: a first virus that expresses a protein comprising an amino acid sequence of SEQ ID NO: 10, or a variant thereof, as an antigenic protein and that is formulated to generate an immunity to the protein or variant thereof in the mammal. The kit also includes a Maraba MG1 virus encoding a protein comprising an amino acid sequence of SEQ ID NO: 10, or a variant thereof, as an antigenic protein, the Maraba MG1 virus formulated to induce the immune response in the mammal; the first virus being immunologically distinct from the Maraba MG1 virus. The antigenic protein expressed by the first virus and the antigenic protein expressed by the Maraba MG1 virus may be identical.

The first virus, the Maraba MG1 virus, or both, may be formulated for administration as isolated viruses.

If the first virus is a negative sense RNA virus, the Maraba MG1 virus, the first virus, or both may include a reverse complement and RNA version of a codon optimized transgene comprising a nucleotide sequence of SEQ ID NO: 11. If the first virus is a DNA virus or a positive sense RNA virus, the first virus may include a codon optimized transgene comprising a nucleotide sequence of SEQ ID NO: 11.

The variant of the protein comprising an amino acid sequence of SEQ ID NO: 10 that is expressed by the first virus, the Maraba MG1 virus, or both, may include at least one tumor associated epitope and be at least 70% identical to SEQ ID NO: 10. Preferably, the variant will be at least 80% identical to SEQ ID NO: 10. More preferably, the variant will be at least 90% identical to SEQ ID NO: 10. Even more preferably, the variant will be at least 30 95% identical to SEQ ID NO: 10.

One of either the Maraba MG1 virus or the first virus may be capable of expressing a protein that comprises the sequence of SEQ ID NO: 10, and the other of the Maraba MG1 virus and the first virus may be capable of expressing a variant of a protein that comprises the sequence of SEQ ID NO: 10. The two viruses may be capable of expressing different variants of the protein that comprises the sequence of SEQ ID NO: 10.

The first virus may be a lentivirus.

According to another aspect, there is provided an isolated Maraba MG1 viral particle having a genome that encodes a protein comprising an amino acid sequence of SEQ ID NO: 10, or a variant thereof.

The genome may include a reverse complement and RNA version of a nucleotide sequence of SEQ ID NO: 11.

The genome may include a nucleotide sequence that is the reverse complement and RNA version of SEQ ID NO: 12.

In another aspect, there is provided a kit for use in inducing an immune response in a mammal. The kit includes: a first virus that expresses a protein comprising an amino acid sequence of SEQ ID NO: 13, or a variant thereof, as an antigenic protein and that is formulated to generate an immunity to the protein or variant thereof in the mammal. The kit also includes a Maraba MG1 virus encoding a protein comprising an amino acid sequence of SEQ ID NO: 13, or a variant thereof, as an antigenic protein, the Maraba MG1 virus formulated to induce the immune response in the mammal; the first virus being immunologically distinct from the Maraba MG1 virus. The antigenic protein expressed by the first virus and the antigenic protein expressed by the Maraba MG1 virus may be identical.

The first virus, the Maraba MG1 virus, or both, may be formulated for administration as isolated viruses.

If the first virus is a negative sense RNA virus, the Maraba MG1 virus, the first virus, or both may include a reverse complement and RNA version of a codon optimized transgene comprising a nucleotide sequence of SEQ ID NO: 14. If the first virus is a DNA virus or a positive sense RNA virus, the first virus may include a codon optimized transgene comprising a nucleotide sequence of SEQ ID NO: 14.

The variant of the protein comprising an amino acid sequence of SEQ ID NO: 13 that is expressed by the first virus, the Maraba MG1 virus, or both, may include at least one tumor associated epitope and be at least 70% identical to SEQ ID NO: 13. Preferably, the variant will be at least 80% identical to SEQ ID NO: 13. More preferably, the variant will be at least 90% identical to SEQ ID NO: 13. Even more preferably, the variant will be at least 95% identical to SEQ ID NO: 13.

One of either the Maraba MG1 virus or the first virus may be capable of expressing a protein that comprises the sequence of SEQ ID NO: 13, and the other of the Maraba MG1 virus and the first virus may be capable of expressing a variant of a protein that comprises the sequence of SEQ ID NO: 13. The two viruses may be capable of expressing different variants of the protein that comprises the sequence of SEQ ID NO: 13.

The first virus may be a lentivirus.

According to another aspect, there is provided an isolated Maraba MG1 viral particle having a genome that encodes a protein comprising an amino acid sequence of SEQ ID NO: 13, or a variant thereof.

The genome may include a reverse complement and RNA version of a nucleotide sequence of SEQ ID NO: 14.

The genome may include a nucleotide sequence that is the reverse complement and RNA version of SEQ ID NO: 15.

Other aspects and features of the present disclosure will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments in conjunction with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure will now be described, by way of example only, with reference to the attached Figures.

FIG. 1A shows the CD8⁺ or CD4⁺ T-cell responses in tumor-bearing mice administered with MG1-hDCT.

FIG. 1B shows the therapeutic efficacy of MG1-hDCT administered as a priming vector only in a metastatic lung cancer mouse model.

FIG. 2 shows the comparison of the immune response of a prime-boost vaccination in C57/BI6 mice with Ad-hDCT as the priming vector and either Maraba MG1-hDCT or VSV-hDCT as the boosting vector.

FIG. 3 shows the T-cell response in a metastatic lung cancer mouse model following Ad-empty or Ad-hDCT, as the priming vector only or following prime-boost vaccination with Ad-hDCT, as the priming vector and either Maraba MG1 GFP or Maraba MG1-hDCT, as the boosting vector.

FIG. 4 shows the survival plot in a metastatic lung cancer mouse model following Ad-empty or Ad-hDCT, as the priming vector only or following prime-boost vaccination with Ad-hDCT, as the priming vector and either Maraba MG1 GFP or Maraba MG1-hDCT, as the boosting vector.

FIG. 5 shows the survival plot in a metastatic brain cancer mouse model following Ad-empty or Ad-hDCT, as the priming vector only or following prime-boost vaccination with Ad-hDCT, as the priming vector and Maraba MG1-hDCT, as the boosting vector.

FIG. 6 is a diagram of the priming vector Ad-MAGEA3, the boosting vector Maraba MG1-MAGEA3 and the prime-boost strategy utilized in a primate toxicity/immunogenicity study.

FIG. 7 shows the average T-cell response in primates given Ad-MAGEA3 as the priming vector and a high or low dose of MG1-MAGEA3 as the boosting vector. The T-cell responses were determined after 5, 13 and 84 days following the boosting vector.

FIG. 8 shows the T-cell responses in individual primates given Ad-MAGEA3 as the priming vector and MG1-MAGEA3 as the boosting vector after 5 days following the boosting vector. The T-cell responses were stratified in relation to the MAGEA3 peptide pool used to stimulate the response.

FIG. 9 shows the survival plot in a metastatic lung cancer mouse model following Ad-hDCT versus Ad-hDCT plus Cyclophosphamide, as the priming vector only or following prime-boost vaccination with Ad-hDCT versus Ad-hDCT plus Cyclophosphamide, as the priming vector and VSV-hDCT, as the boosting vector.

DETAILED DESCRIPTION

The present disclosure provides a kit for use in inducing an immune response in a mammal. The kit includes a first virus that expresses MAGEA3, a Human Papilloma Virus E6/E7 fusion protein, human Six-Transmembrane Epithelial Antigen of the Prostate protein, or Cancer Testis Antigen 1, or a variant thereof, as an antigen and that is formulated to generate an immunity to the antigen in the mammal. The kit also includes a Maraba MG1 virus encoding the same antigen, or a variant of the same antigen, the Maraba MG1 virus formulated to induce the immune response in the mammal. The first virus is immunologically distinct from the Maraba MG1 virus so that it may act as the “prime” in a heterologous prime-boost vaccination.

Prime:boost immunizations can be given with unmatched vaccine delivery methods while using the same antigen, in a ‘heterologous’ prime-boost format; or with matched vaccine delivery methods, in a ‘homologous’ prime-boost. Heterologous prime-boost methods are preferable when using vectored vaccine platforms as homologous vaccination would lead to boosting of responses to both the vector and the transgene in the secondary response. In contrast, a heterologous system focuses the secondary response (that is, the boosted response) on the antigen as responses against the first and the second vector are primary responses, and are therefore much less robust.

In the present disclosure, the first virus and the Maraba MG1 virus are used in a heterologous prime-boost format.

The antigenic proteins listed above are self-antigens already tolerized by the immune system through a tightly controlled process of negative selection in the thymus (Kruisbeek A M and Amsen D, (1996) Curr Opin Immunol 8:233-244; Stockinger B (1999) Adv Immunol 71:229-265) or peripheral tolerization. The major challenge with developing vaccines to these antigenic proteins, and any other self-antigens, is to induce a strong immune response directed selectively against cancer cells. Although a number of tumor associated antigenic peptides have been discovered, the authors of the present disclosure have determined that is impossible to predict which tumor associated antigenic peptides can be successfully used to develop vaccines.

Melanoma antigen, family A,3 (MAGEA3) is a “cancer testis antigen”. The MAGE family of genes encoding tumor specific antigens is discussed in De Plaen et al., Immunogenetics 40:360-369 (1994), MAGEA3 is expressed in a wide variety of tumors including melanoma, colorectal and lung. This protein was used by the authors of the present disclosure as the antigenic protein in both the first virus and the Maraba MG1 virus. The authors also used a variant of the MAGEA3 protein as the antigenic protein in both the first virus and the Maraba MG1 virus.

Human Papilloma Virus (HPV) oncoproteins E6/E7 are constitutively expressed in cervical cancer (Zur Hausen, H (1996) Biochem Biophys Acta 1288:F55-F78). Furthermore, HPV types 16 and 18 are the cause of 75% of cervical cancer (Walboomers J M (1999) J Pathol 189:12-19). The authors of the present disclosure used a fusion protein of the E6/E7 oncoproteins of HPV types 16 and 18 as the antigenic protein. The fusion protein was expressed using a nucleotide sequence coexpressing HPV type 16/18 E6/E7 as a fusion protein, which was mutated to remove oncogenic potential. The fusion protein was used by the authors of the present disclosure as the antigenic protein in both the first virus and the Maraba MG1 virus.

Six-Transmembrane Epithelial Antigen of the Prostate (huSTEAP) is a recently identified protein shown to be overexpressed in prostate cancer and up-regulated in multiple cancer cell lines, including pancreas, colon, breast, testicular, cervical, bladder, ovarian, acute lymphocytic leukemia and Ewing sarcoma (Hubert R S et al., (1999) Proc Natl Acad Sci 96:14523-14528). The STEAP gene encodes a protein with six potential membrane-spanning regions flanked by hydrophilic amino- and carboxyl-terminal domains. This protein was used by the authors of the present disclosure as the antigenic protein in both the first virus and the Maraba MG1 virus.

Cancer Testis Antigen 1 (NYESO1) is a cancer/testis antigen expressed in normal adult tissues, such as testis and ovary, and in various cancers (Nicholaou T et al., (2006) Immunol Cell Biol 84:303-317). Cancer testis antigens are a unique family of antigens, which have restricted expression to testicular germ cells in a normal adult but are aberrantly expressed on a variety of solid tumors, including soft tissue sarcomas, melanoma and epithelial cancers. This protein was used by the authors of the present disclosure as the antigenic protein in both the first virus and the Maraba MG 1 virus.

In contrast to the successful use of the MAGEA3, HPV E6/E7 fusion, the huSTEAP, and the NYESO1 proteins as antigenic proteins in a heterologous prime-boost vaccine, the authors of the present disclosure determined that Epstein-Barr Nuclear Antigen 1 (EBDNA1, SEQ ID NO: 16, encoded by SEQ ID NO: 17) was unable to generate a similar immune response. EBDNA1 is a multifunctional viral protein associated with Epstein-Barr virus (EBV) (Sibille H et al., (2003) Proc Natl Acad Sci 100:10989-10994) and consistently expressed in EBV-associated tumors (Young L S et al., (2004) Nature Reviews—Cancer 4:757-768). EBNA1 has a glycine-alanine repeat sequence that separates the protein into amino- and carboxy-terminal domains (Young L S (2004) Nature Reviews—Cancer 4:757-768). This sequence also seems to stabilize the protein, preventing proteasomal breakdown, as well as impairing antigen processing and MHC class I-restricted antigen presentation. This thereby inhibits the CDB-restricted cytotoxic T cell response against virus-infected cells (Levitskaya J et al., (1995) Nature 375:685-688).

Placenta-specific protein 1 (PLAC-1) is another example of a tumor associated antigenic protein that was unable to generate an immune response in a heterologous prime-boost vaccine.

In the context of the present disclosure, a “variant” of a tumor associated antigenic protein refers to a protein that (a) includes at least one tumor associated antigenic epitope from the tumor associated antigenic protein and (b) is at least 70% identical to the tumor associated antigenic protein. Preferably, the variant will be at least 80% identical to the tumor associated antigenic protein. More preferably, the variant will be at least 90% identical to the tumor associated antigenic protein. Even more preferably, the variant will be at least 95% identical to the tumor associated antigenic protein. Variants with higher sequence identities have increased likelihood that the epitopes are presented in a similar 3-dimensional manner to the wild type antigenic proteins.

Generally, a tumor associated antigenic epitope may be identified by breaking up the whole antigenic protein into overlapping series of peptides, or by generating libraries of random peptides, and looking for T cell responses by stimulating PBMCs or splenocytes from animals vaccinated with the protein target using the peptide pools. Pools having a response identify that peptide as a potential antigenic epitope. This approach is discussed by Morris, G E in Encyclopedia of Life Sciences, 2007, page 1-3 (doi:10.1002/9780470015902.a0002624.pub2).

A database summarizing well accepted antigenic epitopes is provided by Van der Bruggen P, Stroobant V, Vigneron N, Van den Eynde Bin “Database of T cell-defined human tumor antigens: the 2013 update.” Cancer Immun 2013 13:15 and at www.cancerimmunity.org/peptide/.

Tumor associated antigenic epitopes have been already identified for MAGEA3. Accordingly, a variant of the MAGEA3 protein may be, for example, an antigenic protein that includes at least one tumor associated antigenic epitope selected from the group consisting of: EVDPIGHLY (SEQ ID NO: 26), FLWGPRALV (SEQ ID NO: 27), KVAELVHFL (SEQ ID NO: 28), TFPDLESEF (SEQ ID NO: 29), VAELVHFLL (SEQ ID NO: 30), MEVDPIGHLY (SEQ ID NO: 31), REPVTKAEML (SEQ ID NO: 32), AELVHFLLL (SEQ ID NO: 33), WQYFFPVIF (SEQ ID NO: 34), EGDCAPEEK (SEQ ID NO: 35), KKLLTQHFVQENYLEY (SEQ ID NO: 36), RKVAELVHFLLLKYR (SEQ ID NO: 37), ACYEFLWGPRALVETS (SEQ ID NO: 38), VIFSKASSSLQL (SEQ ID NO: 39), VFGIELMEVDPIGHL (SEQ ID NO: 40), GDNQIMPKAGLLIIV (SEQ ID NO: 41), TSYVKVLHHMVKISG (SEQ ID NO: 42), RKVAELVHFLLLKYRA (SEQ ID NO: 43), and FLLLKYRAREPVTKAE (SEQ ID NO: 44); and that is at least 70% identical to the MAGEA3 protein.

It may be desirable for variants of a tumor associated antigenic protein to include only antigenic epitopes that have high allelic frequencies, such as frequencies greater than 40% of the population. Accordingly, preferred examples of variants of MAGEA3 may include proteins that include at least one antigenic epitope selected from the group consisting of: FLWGPRALV (SEQ ID NO: 27), KVAELVHFL (SEQ ID NO: 28), EGDCAPEEK (SEQ ID NO: 35), KKLLTQHFVQENYLEY (SEQ ID NO: 36), and RKVAELVHFLLLKYR (SEQ ID NO: 37) and that is at least 70% identical to the MAGEA3 protein.

The antigen expressed by the first virus does not need to have exactly the same sequence as the antigen expressed by the Maraba MG1 virus. The antigen expressed by Maraba MG1 must only induce an overlapping immune response to the antigen expressed by the first virus. For example, the first virus may express the MAGEA3 and the Maraba MG virus may express a MAGEA3 variant, or vice versa. Since both MAGEA3 and the variant of MAGEA3 induce overlapping immune responses (as they both include at least one identical tumor associated antigenic sequence), the first virus acts as the prime and the Maraba MG1 virus acts as the boost. It is sufficient that the immune response generated in the mammal to the first antigen results in an immune response primarily to the MAGEA3 or MAGEA3 variant when the Maraba MG1 virus is administered.

In the context of the present disclosure, it should be understood that all discussions of, and references to, a ‘protein expressed by a virus’ more exactly refer to a protein expressed by a cell infected with the virus since viruses do not themselves have the capability to express proteins. Similarly, all discussions of, and references to, a ‘virus that expresses a protein’ or ‘virus capable of expressing a protein’ more exactly refer to a virus that includes the genetic information necessary for the protein to be expressed by a cell infected with the virus.

The kit may additionally include an immune-potentiating compound, such as cyclophosphamide (CPA), that increases the prime immune response to the tumor associated antigenic protein generated in the mammal by administrating the first virus. Cyclophosphamide is a chemotherapeutic agent that may lead to enhanced immune responses against the tumor associated antigenic protein. In a synergistic murine melanoma 25 tumor model, CPA administered prior to the priming vector significantly increased survival, while CPA administered prior to the boosting vector did not.

The therapeutic approach disclosed herein combines: (1) a viral vaccine, and (2) Maraba MG1 virus as an oncolytic viral vaccine, both expressing MAGEA3, Human Papilloma Virus E6/E7 fusion protein, human Six-Transmembrane Epithelial Antigen of the Prostate protein, or Cancer Testis Antigen 1, or a variant thereof. Boosting with the oncolytic vaccine may lead to both tumor debulking by the oncolytic virus and a large increase in the number of tumor-specific CTL (cytotoxic T-lymphocytes) in animals primed by the viral vaccine. Paradoxically, this methodology actually generates larger anti-tumor responses in tumor-bearing, as compared to tumor-free, animals since the replication of oncolytic virus is amplified in the tumor-bearing animals, which leads to an increase in the number of antigen-specific Tumor Infiltrating Lymphocytes (TILs), when compared to the replication of oncolytic virus in the tumor-free animals and the associated number of antigen-specific Tumor Infiltrating Lymphocytes (TILs).

The expression products of these genes are processed into peptides, which, in turn, are expressed on cell surfaces. This can lead to lysis of the tumor cells by specific CTLs. The T cell response to foreign antigens includes both cytolytic T lymphocytes and helper T lymphocytes. CD8⁺ cytotoxic or cytolytic T cells (CTLs) are T cells which, when activated, lyse cells that present the appropriate antigen presented by HLA class I molecules. CD4⁺ T helper cells are T cells which secrete cytokines to stimulate macrophages and antigen-producing B cells which present the appropriate antigen by HLA class II molecules on their surface.

The protein “MAGEA3” may be also referred to as “MAGE-A3” and stands for melanoma-associated antigen 3. The antigenic MAGEA3 protein according to the present disclosure is a protein that includes the amino acid sequence of SEQ ID NO: 1. This amino acid sequence may be encoded by the nucleotide sequence of SEQ ID NO: 2. Alternatively, the amino acid sequence may be encoded by a codon optimized transgene that includes the nucleotide sequence of SEQ ID NO: 3. A negative sense RNA virus that expresses the protein of SEQ ID NO: 1 may include a reverse complement and RNA version of a polynucleotide of SEQ ID NO: 2 or 3. A positive sense RNA virus or a DNA virus that expresses the protein of SEQ ID NO: 1 may include a sequence that is SEQ ID NO: 2 or 3.

An example of an antigenic MAGEA3 variant protein according to the present disclosure is a protein that includes the amino acid sequence of SEQ ID NO: 4. This amino acid sequence may be encoded by the nucleotide sequence of SEQ ID NO: 5. A negative sense RNA virus that expresses the protein of SEQ ID NO: 4 may include an RNA polynucleotide which includes a sequence that is a reverse complement and RNA version of SEQ ID NO: 5. A DNA virus or RNA virus that expresses the protein of SEQ ID NO: 4 may include a sequence that is SEQ ID NO: 5.

One example of such a negative sense RNA virus is a Maraba virus that includes the reverse complement and RNA version of SEQ ID NO: 6.

The antigenic protein “E6/E7 fusion protein” or “Human Papilloma Virus E6/E7 fusion protein” according to the present disclosure is a protein that includes the amino acid sequence of SEQ ID NO: 7. This amino acid sequence may be encoded by the nucleotide sequence of SEQ ID NO: 8. A negative sense RNA virus that expresses the protein of SEQ ID NO: 7 may include a reverse complement and RNA version of a polynucleotide of SEQ ID NO: 8. A DNA virus or a positive sense RNA virus that expresses the protein of SEQ ID NO: 7 may include a polynucleotide of SEQ ID NO: 8. One example of such a negative sense RNA virus is a Maraba virus that includes the reverse complement and RNA version of SEQ ID NO: 9.

The protein “huSTEAP” or “human Six-Transmembrane Epithelial Antigen of the Prostate protein” according to the present disclosure is a protein that includes the amino acid sequence of SEQ ID NO: 10. This amino acid sequence may be encoded by the nucleotide sequence of SEQ ID NO: 11. A negative sense RNA virus that expresses the protein of SEQ ID NO: 10 may include a reverse complement and RNA version of a polynucleotide of SEQ ID NO: 11. A DNA virus or RNA virus that expresses the protein of SEQ ID NO: 10 may include a sequence that is SEQ ID NO: 11. One example of such a negative sense RNA virus is a Maraba virus that includes the reverse complement and RNA version of SEQ ID NO: 12.

The protein “NYESO1” or “human Cancer Testis Antigen 1” according to the present disclosure is a protein that includes the amino acid sequence of SEQ ID NO: 13. This amino acid sequence may be encoded by the nucleotide sequence of SEQ ID NO: 14. A negative sense RNA virus that expresses the protein of SEQ ID NO: 13 may include a reverse complement and RNA version of a polynucleotide of SEQ ID NO: 14. A DNA virus or RNA virus that expresses the protein of SEQ ID NO: 13 may include a sequence that is SEQ ID NO: 14. One example of such a negative sense RNA virus is a Maraba virus that includes the reverse complement and RNA version of SEQ ID NO: 15.

The above noted sequences are shown in Appendix A.

The term “mammal” refers to humans as well as non-human mammals. The term “cancer” is used herein to encompass any cancer that expresses the tumor associated antigenic protein (that is: MAGEA3, Human Papilloma Virus E6/E7 fusion protein, human Six-Transmembrane Epithelial Antigen of the Prostate protein, or Cancer Testis Antigen 1) used in the viruses of interest.

For example, when considering MAGEA3 as an antigenic protein, the term “cancer” encompasses any cancer that expresses MAGEA3 as an antigen. Examples of such a cancer include, but are not limited to, melanoma, non-small cell lung cancer, head and neck cancer, colorectal cancer, and bladder cancer.

When considering E6/E7 fusion protein as an antigenic protein, the term “cancer” encompasses any cancer that expresses E6 and E7 proteins as antigenic proteins. Examples of such a cancer include, but are not limited to, cervical cancer.

The first virus, the Maraba MG1 virus, or both may be independently administered to the mammal intravenously, intramuscularly, intraperitoneally, or intranasally. Following administration of the viruses, an immune response is generated by the mammal within an immune response interval, e.g. within about 4 days, and extending for months, years, or potentially life.

The first virus may be any virus that induces an immune response to the tumor associated antigenic protein or variant thereof after the first virus is administered to the patient. Viruses that may be used according to the present disclosure include, for example: adenovirus (Ad), poxvirus, retrovirus, and alpha virus. An example of a poxvirus is vaccinia virus. An example of a retrovirus is lentivirus. An example of an alpha virus is semliki forest virus.

To establish an immune response to the tumor associated antigenic protein or variant thereof, vaccination using the first virus and the Maraba MG1 virus may be conducted using well-established techniques. As one of skill in the art will appreciate, the amount of virus required to generate an immune response will vary with a number of factors, including, for example, the selected antigen, the viral vector used to deliver the antigen, and the mammal to be treated, e.g. species, age, size, etc. In this regard, for example, intramuscular administration of at least about 10⁷ PFU of Adenoviral vector to a mouse is sufficient to generate an immune response. A corresponding amount would be sufficient for administration to a human to generate an immune response.

Once an immune response has been generated in the mammal by administration of the first virus, Maraba MG1 virus encoding the tumor associated antigenic protein or a variant thereof is administered in an amount suitable for oncolytic viral therapy within a suitable immune response interval. A suitable immune response interval may be, for example, at least about 24 hours, preferably at least about 2-4 days or longer, e.g. at least about 1 week, or at least about 2 weeks. The amount of Maraba MG1 virus suitable for oncolytic viral therapy will vary with the mammal to be treated, as will be appreciated by one of skill in the art. For example, 10⁸ PFU of Maraba MG1 virus encoding MAGEA3 administered IV to a mouse is sufficient for oncolytic therapy. A corresponding amount would be sufficient for use in a human.

Maraba MG1 virus encoding tumor associated antigenic protein or a variant thereof may be prepared by incorporating a reverse complement of a transgene encoding the tumor associated antigenic protein or a variant thereof into the Maraba MG1 virus using standard recombinant technology. For example, the reverse complement of the transgene may be incorporated into the genome of the Marama MG1 virus, or alternatively, may be incorporated into the virus using a plasmid incorporating the transgene. The transgene encoding the tumor may be a codon optimized transgene.

EXAMPLES

The oncolytic Maraba MG1 is a potent oncolytic vaccine platform. While unable to prime detectable responses against a melanoma-associated antigen, Maraba MG1-vaccine displayed the ability to boost preexisting tumor-specific CD4⁺ and CD8⁺ T-cell immunity. When applied to the treatment of syngeneic murine melanoma tumor models, Maraba-MG1-mediated recall immunization resulted in an extension of the median survival with complete remission in more than 20% of the animals treated.

In a primate toxicity study heterologous prime-boost vaccination with an Ad-MAGEA3 prime followed by a Maraba-MG1-MAGEA3 boost resulted in T-cell responses that were comparable to those obtained in syngeneic murine tumor models demonstrating that in an outbred primate population the prime-boost oncolytic vaccine strategy gives immune responses comparable to animal models where tumors can be engrafted and a dramatic extension of survival is attained.

The authors of the present disclosure also determined that proteins having the sequence SEQ ID NOs: 7, 10, or 13 could be used to stimulate an immune response in a patient using a heterologous prime boost with Maraba MG1. In contrast, the authors of the present disclosure determined that administration of a first virus expressing EBDNA-1 protein or Placenta-specific protein 1 (PLAC-1) followed by administration of Maraba-MG1 expressing EBDNA-1 protein or PLAC-1, respectively, was unable to stimulate an immune response.

Example 1: MG1-hDCT is a Weak Priming Vector but a Potent Boosting Vector

Ad-empty and Ad-hDCT are replication-deficient adenoviruses (E1/E3-deletion) based on the human serotype 5 (Lane C. et al., (2004) Cancer Research 64:1509-1514; Ng P. et al., (2001) Mol Ther 3:809-815). The replication-deficient adenovrius vector was engineered to express the hDCT transgene, which encodes the full length human melanoma associated antigen DCT (dopachrome tautomerase) while Ad-empty has no transgene. The resulting adenovirus vector is termed “Ad-hDCT”.

The MG1 variant of Maraba virus was engineered to express the human form of the melanoma-associated antigen hDCT transgene. The resulting MG1 virus vector is termed “MG1-hDCT” or “Maraba MG1-hDCT”. Other virus vectors are named using a similar convention.

Recombinant Maraba and VSV were generated by transgene insertion between the G and L viral genes. VSV-hDCT derives from the wild-type Indiana strain of the VSV (Bridle B W. et al. (2009) 17:1814-1821; Lawson N D. et al., (1995) Proc Natl Acad Sci USA 92:4477-4481). MG1-GFP (Green Flourescent Protein used as a control non-immunogenic transgene insertion) and MG1-hDCT derive from the attenuated strain MG1 of Maraba virus. Prior to in vivo studies, DCT (and GFP) expression from the virus was confirmed by western blot of lysates from infected Vero cells cultured in alpha-MEM containing 10% FBS, 2 mM L-glutamine, 100 U/ml penicillin, and 100 mg/ml streptomycin (all from Invitrogen, Grand Island, N.Y.).

The therapeutic efficacy of MG1-hDCT administered as a monotherapy was evaluated initially. In order to generate lung metastases, C57BI/6 mice (8-10 weeks old at study initiation) were injected i.v. with 2.5×10⁵ B16-F10 cells (murine melanoma cells expressing the murine DCT antigen) in 200 μl saline water. The oncolytic vaccine was injected systemically 5 or 14 days later and T-cell responses against the melanoma antigen DCT were measured in the blood at day 19. The virus was administered systemically at a high dose (10⁹ pfu i.v in 200 μl PBS). T-cell responses were measured by isolating PBMCs or splenocytes and stimulating them with the SVYDFFVWL (SEQ ID NO: 45) (SVY) or KFFHRTCKCTGNFA (SEQ ID NO: 46), (KFF) peptides corresponding to the MHC-I or MHC-II restricted immunodominant epitopes of DCT, respectively. Responding T-cells were detected after intracellular cytokine staining (ICS) for IFN-γ by flow cytometry.

As shown in FIGS. 1A and 1B, MG1-hDCT was unable to prime DCT-specific CD8⁺ or CD4⁺ T-cell responses in tumor-bearing mice (FIG. 1A). Administered alone, the MG1-hDCT vaccine did not improve tumor outcome. Indeed, mice treated 14 days post-tumor challenge reached endpoint in a similar timeframe as untreated mice: after 20 days for the Ad-empty control group versus 21 days for the Ad-empty+MG1-hDCT group (FIG. 1B). Moreover, survival was not extended even when mice were treated with MG1-hDCT as early as 5 days after tumor engraftment (MG1-hDCT group, FIG. 1B). In conclusion, not only did MG1-hDCT fail to induce anti-DCT immunity but its oncolytic activity offered no therapeutic benefit. These results demonstrate that MG1-hDCT is unable to prime significant T-cell responses against the tumor antigen DCT and is thus a weak priming vector.

It was previously reported that an oncolytic VSV vector serves as a potent booster of pre-existing immunity (Bridle B W. et al., (2010) Mol Ther 184:4269-4275; WO 2010/105347). In the present disclosure, the ability of Maraba MG1 virus to serve as a booster vaccine was examined. Adenoviral vectors were used as priming vectors and administered intramuscularly (i.m.) at a total dose of 2×10⁸ pfu (1×10⁸ pfu in 500 PBS per thigh). For adenovirus injection, mice were anesthetized in a sealed chamber containing 5% inhalation isoflurane. Using Ad-hDCT as a priming vector, MG1-hDCT was evaluated as a booster of pre-existing DCT-specific responses. To evaluate Maraba virus as a boosting vector, various routes of administration were evaluated. An oncolytic dose of 1×10⁹ pfu of virus was administered that is well tolerated in this mouse strain and an interval of 12 days post-Ad priming was selected as this was the longest interval that would be feasible in the tumor model. When this dose of MG1-Maraba-hDCT was administered by intravenous (i.v.), intranasal (i.n.) and intramuscular (i.m.) routes, the i.v. route proved to be far superior as measured by ICS for IFN-γ in peripheral CD8⁺ T-cells: 28.33%±3.82 by i.v. versus 4.73%±1.52 i.n. versus 13.84%±1.88 i.m. The responses were measured at day 5 post-Maraba administration coinciding with the peak of the MG1-hDCT-mediated boost response. In the intravenously boosted animals a significant proportion of DCT-specific CD8⁺ T-cells was also measured in the spleen with a 3-fold increase in mice administered with both vaccine vectors compared to animals primed only: 3.45%±0.45 in Ad-hDCT group versus 11.02%±2.14 in the Ad-hDCT+MG1-hDCT immunized animals (p=0.0085**). While Ad-hDCT was unable to induce a detectable DCT-specific CD4⁺ T-cell population in the blood and a barely detectable population in the spleen, the MG1 Maraba-hDCT booster was able to generate clear systemic CD4⁺ T-cell response but only when administered i.v. (0.30%±0.11). The response was also detectable in the spleen with 0.14%±0.03 of splenic CD4⁺ T-cells reacting to DCT KFF peptide exposure. Similar to VSV, maximal immune boosting by MG1 Maraba virus is achieved by i.v. administration. In conclusion, systemic delivery of a Maraba-vectored vaccine at a dose of 10⁹ pfu appeared to allow for efficient boosting of both antigen-specific CD8⁺ and CD4⁺ T-cell populations. For this reason, this route and dose were used for Maraba MG1 administration in subsequent in vivo experiments.

To show that Maraba MG1-hDCT is a more potent boosting vector than VSV-hDCT, C57/B16 mice were primed with Ad-hDCT (Ad-BHG was included as a control vector lacking a transgene) and then boosted with an intravenous dose of either VSV-hDCT or Maraba-hDCT 14 days later. Immune analysis of CD8⁺ T cell responses were measured in peripheral blood at day 5 post-boosting vector. At an equivalent dose the response induced by Maraba vaccination was 3-8 fold as large as the VSV-induced responses (FIG. 2).

Example 2: MG1-hDCT Vaccine Strategy in Murine Models of Cancer

The therapeutic efficacy of MG 1-hDCT administered as a boosting vector was subsequently investigated. Five days following B16-F10 engraftment to generate lung metastases in animals, animals received an Ad-hDCT priming vaccine and this was followed 9 days later by a single i.v. dose of MG1 Maraba-hDCT as an oncolytic booster vaccine. Ad-hDCT prime-MG1-hDCT boost vaccination generated a very strong DCT-specific CD8⁺ T-cell response (mean % IFN-γ⁺ CD8⁺ T-cells=27.54±2.17, FIG. 3) that was 14 times higher than in non-boosted mice (1.95%±0.29 in Ad-hDCT group and 1.91%±0.59 in Ad-hDCT+MG1-GFP group, FIG. 3). Similarly, DCT-specific CD4⁺ T-cell responses were measured in MG1-hDCT boosted animals while rarely detected in primed only mice (mean % IFN-γ⁺ CD4⁺ T-cells=0.25%±0.06 in Ad-hDCT+MG1-hDCT group versus <0.05% in Ad-hDCT and Ad-hDCT+MG1-GFP groups, FIG. 3).

Looking at treatment outcome, Ad-hDCT immunization allowed a 10-day extension of the median survival compared to untreated mice: 31 days for Ad-hDCT treatment versus 20.5 days for Ad-empty group (FIG. 4). Ad-hDCT treatment followed by MG1 Maraba-GFP oncolytic treatment did not improve survival (27.5 days median survival for Ad-hDCT+MG1-GFP group, FIG. 4). However, boosting anti-tumor immunity with the Maraba MG1-DCT vaccine dramatically improved tumor outcome with a 20-day extension of the median survival compared to Ad-hDCT primed only animals (51 days for Ad-hDCT+MG1-hDCT group, FIG. 4). More importantly, the oncolytic MG1-hDCT booster treatment resulted in 23.3% long-term survival (FIG. 4).

In order to characterize the respective contribution of tumor-specific CD4⁺ and CD8⁺ T-cell responses in the therapeutic efficacy, each T-cell compartment was selectively depleted (data not shown). Depletion of the CD8⁺ T-cell population at the time of the boost abrogated the therapeutic benefit of MG1-hDCT administration. On the contrary, CD4⁺ T-cells depletion appeared not to affect significantly the therapeutic efficacy indicating that Maraba immune boosting of CD8⁺ T cells is CD4⁺-independent. While the critical role of CD8⁺ T-cells in controlling tumor growth is admitted, these results show that boosting tumor-specific CD8⁺ T-cells with Maraba vaccine is a potent way of improving cancer therapy.

Finally, the efficacy of the prime-boost strategy involving Maraba vaccine was also evaluated in a very challenging intracranial B16-F10 model of metastatic melanoma brain cancer. Ad-hDCT-mediated immunotherapy significantly improved survival of melanoma brain met-bearing mice with a median extended from 15 days for Ad-empty controls to 25.5 days for the Ad-hDCT group (FIG. 5). As previously reported, such therapeutic efficacy demonstrates the ability of the tumor-specific effector T-cells raised to cross the blood-brain barrier and infiltrate the tumor bed (Bridle B W. et al., (2010) Mol Ther 184:4269-4275). The additional administration of a Maraba MG1-hDCT oncolytic booster further improved tumor outcome with a median survival reaching 42 days together with cures observed in 21.4% of treated animals (Ad-hDCT+MG1-hDCT group, FIG. 5).

Example 3: Failure of Vaccine Strategy to Induce an Anti-mPLAC1 T Cell Response

Although Maraba MG1 and VSV were able to act as boosting vectors using hDCT as a tumor associated antigen, not all tumor associated antigens can be used in a heterologous prime-boost vaccine strategy. The authors of the present disclosure tested a heterologous prime-boost vaccine strategy using huAd5-mPLAC1 as the priming vector and VSV-mPLAC1 as the boosting vector.

PLAC1 is a recently described tumor associated antigen expressed in the placenta but has also been reported in several tumor cell lines and in tumors of patients breast, lung, liver, gastric and colorectal cancers (Silva, W A et al., (2007) Cancer Immun 7:18).

Ad-mPLAC1 is a replication-deficient adenoviruses (E1/E3-deletion) based on the human serotype 5 (Lane C. et al., (2004) Cancer Research 64:1509-1514; Ng P. et al., (2001) Mol Ther 3:809-815). The replication-deficient adenovirus vector was engineered to express the mPLAC1 transgene, which encodes the full length murine antigen PLAC1 (placenta-specific 1), the resulting adenovirus vector is termed “Ad-mPLAC1” or “huAd5-mPLAC1”.

VSV virus was engineered to express the human form of the melanoma-associated antigen mPLAC1 transgene. The resulting VSV-virus vector is termed “VSVmPLAC1”. Recombinant VSV was generated by transgene insertion between the G and L viral genes. VSV-mPLAC1 derives from the wild-type Indiana strain of the VSV (Bridle B W. Et al. (2009) 17:1814-1821; Lawson N D. et al., (1995) Proc Natl Acad Sci USA 92:4477-4481).

C57BI/6 mice were primed with Ad-mPLAC1 (2×10⁹ PFU IM injection) and then boosted with a single i.v.dose.of VSV-mPLAC1 (2×10⁹ PFU) 14 days later. T-cell responses were measured by isolating splenocytes and stimulating them with individual 15 mmer peptides form an overlapping PLAC1 peptide library for a total of 6 hours with golgi plug added 1 hour into the stimulation. Following stimulation the splenocytes were stained for CD4, CD8 and IFNγ and analyzed on FACSCanto and FlowJo. Responding T-cells were detected after intracellular cytokine staining (ICS) for IFN-γ by flow cytometry. None of the mPLAC1 peptides were able to stimulate IFN-γ production in either CD8 or CD4 T cells.

Example 4: Construction of Oncolytic Vaccine Vectors with MAGEA3 or a Variant Thereof

Ad-MAGEA3 is a replication-deficient adenovirus (E1/E3-deletion) based on the human serotype 5 (Lane C. et al., (2004) Cancer Research 64:1509-1514; Ng P. et al., (2001) Mol Ther 3:809-815) containing the full-length human MAGEA3 gene. Maraba MG1-hMAGEA3 has been developed and contains the codon-optimized full length human MAGEA3 gene inserted between the G and L viral genes of the MG1 double mutant of Maraba virus (Brun J. et al., (2010) Mol Ther 18:1440-1449). The MAGEA3 sequence (NCBI Gene ID: 4102 www.ncbi.nlm.nih.gov/gene/4102) was codon optimized for expression in mammalian cells and then synthesized with a FLAG tag on 3′ end and with Mlul restriction sites on both 3′ and 5′ ends. This sequence was ligated into the shuttle vector pMRB-MG1/pNF at its Mlul site (between G and L genes) which contains part of the Maraba-MG1 genome from the beginning of G to the end of L genes, flanked by Kpnl and Nhel sites, respectively. The entire region from Kpnl to Nhel, now containing MAGEA3 Flag between G and L was then removed from pMRB-MG1/pNF and ligated back into the pMRB-MG1 genomic plasmid using Kpnl and Nhel sites. Maraba-MG1-MAGEA3 Flag was then rescued and plaque purified. This is illustrated in FIG. 6.

A full length human MAGEA3 protein expressed by the adenovirus may include the amino acid sequence of SEQ ID NO: 1. The adenovirus may include a nucleotide sequence of SEQ ID NO: 2. Alternatively, the amino acid sequence may be encoded by a codon optimized transgene that includes the nucleotide sequence of SEQ ID NO: 3. Accordingly, the adenovirus may include the codon-optimized nucleotide sequence of SEQ ID NO: 3.

The Maraba MG1 virus may include a reverse complement and RNA version of a nucleotide sequence of SEQ ID NO: 2. Alternatively, the amino acid sequence may be encoded by a codon optimized transgene that includes the nucleotide sequence of SEQ ID NO: 3. Accordingly, the Maraba MG1 virus may include the reverse complement and RNA version of the codon-optimized nucleotide sequence of SEQ ID NO: 3.

One variant of MAGEA3 is a protein that includes the amino acid sequence of SEQ ID NO: 4. This amino acid sequence may be encoded by the nucleotide sequence of SEQ ID NO: 5. The adenovirus may include a nucleotide sequence of SEQ ID NO: 5. The Maraba MG1 virus may include a reverse complement and RNA version of a nucleotide sequence of SEQ ID NO: 5.

A negative sense RNA virus, such as a Maraba virus, that expresses the protein of SEQ ID NO: 4 may include an RNA polynucleotide which includes a sequence that is a reverse complement and RNA version of SEQ ID NO: 6.

Example 5: MG1-MAGEA3 Vaccine Immune Response in Healthy Primates

Healthy cynomolgous monkeys were used in a study designed to collect toxicity and immunogenicity data for developing the potential MG1-MAGEA3 oncolytic vaccine for human use. The use of the cynomolgous monkeys maximizes the likelihood of identifying responses that are quantitatively and qualitatively similar to those expected in humans. Prior to study start primates were acclimated for 4-6 weeks from the time of animal arrival until the time of vascular access port implantation surgery. After a minimum of 2-3 weeks following surgery, animals were vaccinated with a non-replicating adenovirus Ad-MAGEA3 priming vector, injected in each leg, 0.5 ml per dose totaling 1×10¹⁰ pfu by slow IM injection. For the Ad-MAGEA3/MG1-MAGEA3 prime boost study, Ad-MAGEA3 prime occurred at either 2 weeks (−14 days) or 4 weeks (−28 days) prior to MG1-MAGEA3 boost. Therefore Ad-MAGEA3 administration occurred on Day −14 or on Day −28 and MG1-MAGEA3 boost on Days 0 and 3. The rationale for Ad-MAGEA3 dosage level comes from the literature, and from previous experiments demonstrating that a dose of 1×10¹⁰ pfu in Macaques (and humans) is a safe dose with no observed toxicities (Bett et al. Vaccine, 2010). For animals in the 2 week boosted group, MG1-MAGEA3 virus was injected i.v. at either a low dose 1×10¹⁰ or a high dose 1×10¹¹ at experiment days 0 and 3 (14 and 17 days after Ad-MAGEA3). For animals in the 4 week boosted group, MG1-MAGEA3 virus was injected i.v. at either a low dose 1×10¹⁰ or a high dose 1×10¹¹ at experiment days 0 and 3, (28 and 31 days after the Ad-MAGEA3). Boosting Virus was infused in 30 mL of sterile buffered saline (pH 7.5) over 30 minutes through the vascular access port. The rationale for MG 1-MAGEA3 low dosage level comes from pre-clinical studies that demonstrate that the murine maximum tolerable dose is 1×10⁹. The relative body surface area scale-up to Macaques equates this to 3.5×10¹⁰ total pfu. The rationale for MG1-MAGEA3 high dosage level comes from a pilot Non-Human Primate (NHP) toxicology study, where there was no observed toxicity at a dose level of 2×10¹¹ pfu. Animals in the prime boost study were either sacrificed early (Day 14) or late (Day 84). For the Ad-MAGEA3/MG1-MAGEA3 prime boost study, blood samples were taken from all animals at 5 distinct time points. For animals in the 2 week heterologous prime-boost cohort, blood samples were collected prior to any vaccination and on a day prior to Day −14 (Baseline) and on experiment Days 5, 13 and 84. For animals in the 4 week heterologous prime-boost cohort, blood samples were collected prior to any vaccination and on a day prior to Day −28 (Baseline), and on experiment Days 5, 13, and 84.

To assess immune responses in the primates to the heterologous prime-boost vaccination with Ad-MAGEA3/MG1-MAGEA3, Peripheral Blood Mononuclear Cells (PBMCs) were incubated for 4 hours (last 3 hours in presence of Brefeldin A) with a pool of 10 hMAGE-A3 peptides for T-cell (re-) stimulation (or left unstimulated for evaluation of the background). Peptides were from an overlapping peptide library covering the whole hMAGE-A3 antigen from N to C-termini in 87 peptides (15-mer each). After stimulation, T-cells were stained with fluorescent anti-CD8 and anti-CD4 antibodies for 25 minutes. After this surface staining, cells were permeabilized and fixed with BD Cytofix/Cytoperm for 20 minutes. Then, hMAGE-A3-specific T-cells were detected by looking at cytokine expression by intracellular staining with fluorescent anti-IFNγ and anti-TNFα antibodies for 25 minutes. Cell analysis was performed on BD Canto flow cytometer.

FIG. 7 shows the average CD8⁺ T-cell immune responses of monkeys given high and low dose MG1-MAGEA3 as a boosting vector following an Ad-MAGEA3 prime. In the low dose MG1-MAGEA3 animals there is a significant increase in CD8⁺ T-cell response 5 days following the boost, which drops off over time while in the high dose MG1-MAGEA3 animals there is a similar significant increase in CD8⁺ T-cell response 5 days following the boost, which is sustained at a higher level over time. FIG. 8 shows that all of the animals in the study exhibited a significant increase in CD8⁺ T-cell response 5 days following the boost with MG1-MAGEA3 irrespective of high or low dose. These peak T-cell responses in Primates demonstrate that in an outbred population the prime-boost oncolytic vaccine strategy gives immune responses comparable to animal models where tumors can be engrafted and a dramatic extension of survival is attained.

Example 6: Construction and Immune Testing of Lentiviral Priming Vectors and Oncolytic Vaccine Vectors Expressing Human Papilloma Virus E6/E7 Fusion Protein

The HPV transgene is a fusion of HPV serotype 16 full-length wild-type E6 (gi/4927720/gb/AAD33252.1/AF125673_1 E6 Human papillomavirus type 16) and E7 (gi/4927721/gb/AAD33253.1/AF125673_2 E7 Human papillomavirus type 16) sequences and HPV serotype 18 full-length wild-type E6 (gi/137758/sp/P06463.1/VE6_HPV18 RecName: Full=Protein E6) and E7 (gi/137792/sp/P06788.2/VE7 HPV18 RecName: Full=Protein E7) sequences with deletions in all 4 nucleotide sequences to remove zinc fingers required for Rb or p53 binding (removing oncogenic potential of the proteins). The resulting fusion protein has a flexible glycine linker plus AAY sequence (which serves as a proteasomal cleavage site to ensure that each antigen is proteolytically degraded to the peptides normally generated for antigen presentation). This codon-optimized fusion nucleotide sequence gives rise to a 527 amino acid HPV16/18 E6/E7 fusion protein (SEQ ID NO: 7).

Lentiviruses expressing Human Papilloma Virus E6/E7 fusion transgene were made using the pDY.EG.WS lentivirus vector. The modified HPV transgene was PCR amplified using primers containing the EcoRI restriction site (forward primer ACTGGAATTCATGCATCAGAAGCGAACTGC, SEQ ID NO: 18) and the BamHI restriction site (reverse primer ACTGGGATCCTCACTGCTGGGAGGCACAC, SEQ ID NO: 19). The HPV transgene PCR product was agarose gel purified. The pDY.EG.WS lentivirus vector was cut at the EcoRI and BamHI sites to remove eGFP, was agarose gel purified, and was subjected to dephosphorylation using CIAP (Invitrogen Catalogue 18009-019). The cut vector was then subjected to additional agarose gel purification. The HPV transgene PCR product was then ligated into the EcoRI/BamHI cut vector using T4 DNA ligase (Invitrogen). The ligation reaction was subjected to a transformation using competent cells, and plasmid DNA from positive colonies was subjected to mini-prep amplification. The pDY.EG.WS lentivirus vector expressing the modified HPV transgene was then subjected to maxi-prep amplification. The lentivirus expressing Human Papilloma Virus E6/E7 fusion transgene were rescued on 293T cells after transfection of 6.4 μg of each of three plasmids: the pDY.EG.WS lentivirus vector expressing the modified HPV transgene, the packaging pCMV-8.84 plasmid, and the envelope pMD2G plasmid. Virus supernatants were pooled, and filtered through a 0.45 μM filter and centrifuged for 120 minutes at 50,000×g at 16° C. The lentivirus expressing Human Papilloma Virus E6/E7 fusion transgene was resuspended in PBS, and stored at −80° C.

Maraba MG1 was engineered to contain a Papilloma Virus E6/E7 fusion transgene inserted between the G and L viral genes of the MG1 double mutant of Maraba virus (Brun J. et al., (2010) Mol Ther 18:1440-1449). The transgene sequence (SEQ ID NO: 8) was codon optimized for expression in mammalian cells. The resulting Maraba MG1 containing the HPV E6/E7 is designated, generally, “Maraba-MG1-HPV E6/E7”. A modified Maraba MG1 backbone was used to facilitate cloning. A silent mutation was introduced into the L gene of the Maraba MG1 genome backbone to remove one of the Mlul sites. The second Mlul site was replaced with a BsiWI site at the cloning region between G and L. These modifications to the Maraba MG1 genome backbone allowed for a more direct cloning system than that described in the Brun et al. paper as it avoids using the shuttle plasmid pMRB-MG1/pNF. The HPV E6/E7 fused transgene sequence was ligated into the modified Maraba MG1 genome backbone at its Mlul site and BsiWI site (at cloning region between G and L) The Maraba-MG1-HPV E6/E7 was then rescued (as previously described in Brun et al., (2010) Mol Ther 18:1440-1449), plaque purified once, and subjected to opti-prep purification.). The Maraba-MG1-HPV E6/E7 has a genomic sequence that is the reverse complement and RNA version of SEQ ID NO: 9.

Generally, animals were immunized by administration of the priming vector (lentivirus-HPV E6/E7+poly I:C as an adjuvant) at day 0 and by administration of 1e9 PFU of the boosting vector (Maraba-MG1-HPV E6/E7) at day 14. Control animals were prime-boosted with viral vectors encoding GFP instead of the HPV E6/E7 transgene as a control non-immunogenic transgene insertion. Analysis of the prime response was conducted at day 14 and of the boost response at day 19. Each lentivirus-HPVE6/E7 preparation was made with 250 ug poly I:C added as an adjuvant to the priming virus and then split between 5 animals for each virus. Mice were anesthetized with isoflurane and 30 uL of lentivirus-HPV E6/E7/poly I:C was injected into each hind foot pad. The remaining virus was injected subcutaneously near the left inguinal lymph node. 14 days after prime, blood was collected and analyzed by flow cytometry. Mice were then boosted with 1×10⁹ PFU MG1-HPV E6/E7 intravenously. 5 days following the boost, blood was drawn and immune responses were assessed by flow cytometry.

Immune analysis was performed as follows: Blood was collected via retro-orbital bleeding using heparinzied capillary tube and blood was collected into heparin. Red blood cells were then lysed using ACK lysis buffer and the resulting PBMCs were analyzed for immune responses to the tumor antigens. PBMCs were either incubated in the absence of peptide or stimulated with 2 ug/mL peptides (RAHYNIVTF) (SEQ ID NO: 47) for a total of 5 hours with golgi plug added 1 hour into the stimulation. Following stimulation the PBMCs were stained for CD4, CD8 and IFNγ and analyzed on FACSCanto and FlowJo. Responding T-cells were detected after intracellular cytokine staining (ICS) for IFN-γ by flow cytometry. Values from unstimulated PBMCs were considered background and subtracted from values obtained from stimulated PBMCs. Data represents mean+/−SEM. In Table 1 it is demonstrated that the HPV E6/E7 peptides were able to stimulate IFN-γ production in CD8 cells indicating the existence of an immune response.

TABLE 1 IMMUNE RESPONSE to HPV E6/E7 PRIME-BOOST Percentage of CD8 T Cells Secreting Interferon (IFN) ^(γ) Immune Group Lentivirus-HPV E6/E7 Stimulatory Control Group Prime Peptide Lentivirus-GFP Prime MG1-HPV E6/E7 Boost Epitope MG1-GFP Boost (N = 5) RAHYNIVTF 0.0033 ± 0.0033 0.03 ± 0.025 0.036 ± 0.012 5.9 ± 2.7 (SEQ ID (after prime) (after boost) (after prime) (after boost) NO: 47)

Example 7: Construction and Immune Testing of Lentiviral Priming Vectors and Oncolytic Vaccine Vectors Expressing Cancer Testis Antigen 1

The NYESO1 transgene is full-length wild-type sequence (SEQ ID NO: 14) codon-optimized for expression in human and mouse to give rise to a 180 amino acid protein (SEQ ID NO: 13).

Lentiviruses expressing Cancer Testis Antigen 1 transgene were made using the pDY.EG.WS lentivirus vector. The NYESO1 transgene was PCR amplified using primers containing the BamHI restriction site (forward primer ACTGGGATCCATGCAGGCCGAGGGCAGAG, SEQ ID NO: 20) and the BamHI restriction site (reverse primer ACTGGGATCCTCATCTTCTCTGGCCGCTGG, SEQ ID NO: 21). The NYESO1 transgene PCR product was agarose gel purified. The pDY.EG.WS lentivirus vector was cut at the BamHI site to remove eGFP, was agarose gel purified, and was subjected to dephosphorylation using CIAP (Invitrogen Catalogue 18009-019). The cut vector was then subjected to additional agarose gel purification. The NYESO1 transgene PCR product was then ligated into the BamHI cut vector using T4 DNA ligase (Invitrogen). The ligation reaction was subjected to a transformation using competent cells, and plasmid DNA from positive colonies was subjected to mini-prep amplification. The pDY.EG.WS lentivirus vector expressing the modified HPV transgene was then subjected to maxi-prep amplification. The lentivirus expressing NYESO1 transgene were rescued on 293T cells after transfection of 6.4 μg of each of three plasmids: the pDY.EG.WS lentivirus vector expressing the NYESO1 transgene, the packaging pCMV-8.84 plasmid, and the envelope pMD2G plasmid. Virus supernatants were pooled, and filtered through a 0.45 μM filter and centrifuged for 120 minutes at 50,000×g at 16° C. The lentivirus expressing NYESO1 transgene was resuspended in PBS, and stored at −80° C.

Maraba MG1 was engineered to contain Cancer Testis Antigen 1 transgene inserted between the G and L viral genes of the MG1 double mutant of Maraba virus (Brun J. et al., (2010) Mol Ther 18:1440-1449). The transgene sequence was codon optimized for expression in mammalian cells. The resulting Maraba MG1 containing the NYESO1 protein is designated as “Maraba-MG1-NYESO1” or “MG1-NYESO1”.

The NYESO1 transgene was ligated into the shuttle vector pMRB-MG1/pNF at its Mlul site (between G and L genes) which contains part of the Maraba-MG1 genome from the beginning of G to the end of L genes, flanked by Kpnl and Nhel sites, respectively. The entire region from Kpnl to Nhel, now containing the NYESO1 transgene inserted between G and L was then removed from pMRB-MG1/pNF and ligated back into the pMRB-MG1 genomic plasmid using Kpnl and Nhel sites. The Maraba-MG1-NYESO1 was then rescued (as previously described Brun J. et al., (2010) Mol Ther 18: 1440-1449). The Maraba-MG1-NYESO1 was plaque purified 3 times, and purified via sucrose cushion purification. The Maraba-MG1-NYESO1 virus has a genomic sequence that is the reverse complement and RNA version of SEQ ID NO: 15.

Generally, animals were immunized by administration of the priming vector (lentivirus-NYESO1+poly I:C as an adjuvant) at day 0 and by administration of 1e9 PFU of the boosting vector (Maraba-MG1-NYESO1) at day 14. Control animals were prime-boosted with viral vectors encoding GFP instead of the NYESO1 transgene as a control non-immunogenic transgene insertion. Analysis of the prime response was conducted at day 14 and day 19. Each lentivirus-NYESO1 preparation was made with 250 ug poly I:C added as an adjuvant to the priming virus and then split between 5 animals for each virus. Mice were anesthetized with isoflurane and 30 uL of lentivirus-NYESO1/poly I:C was injected into each hind foot pad. The remaining virus was injected subcutaneously near the left inguinal lymph node. 14 days after prime, blood was collected and analyzed by flow cytometry. Mice were then boosted with 1×10⁹ PFU MG1-NYESO1 intravenously. Five days following the boost, blood was drawn and immune responses were assessed by flow cytometry.

Immune analysis was performed as follows: Blood was collected via retro-orbital bleeding using heparinzied capillary tube and blood was collected into heparin. Red blood cells were then lysed using ACK lysis buffer and the resulting PBMCs were analyzed for immune responses to the tumor antigens. PBMCs were either incubated in the absence of peptide or stimulated with 2 ug/mL peptides (RGPESRLL) (SEQ ID NO: 48) for a total of 5 hours with golgi plug added 1 hour into the stimulation. Following stimulation the PBMCs were stained for CD4, CD8 and IFNγ and analyzed on FACSCanto and FlowJo. Responding T-cells were detected after intracellular cytokine staining (ICS) for IFN-γ by flow cytometry. Values from unstimulated PBMCs were considered background and subtracted from values obtained from stimulated PBMCs. Data represents mean+/−SEM. In Table 2 it is demonstrated that the NYESO1 peptides were able to stimulate IFN-γ production in CD8 cells indicating the existence of an immune response.

TABLE 2 IMMUNE RESPONSE to NYESO1 PRIME-BOOST Percentage of CD8 T Cells Secreting Interferon (IFN) ^(γ) Immune Group Lentivirus-NYESO1 Stimulatory Control Group Prime Peptide Lentivirus-GFP Prime MG1-NYESO1 Boost Epitope MG1-GFP Boost (N = 5) RGPESRLL 0 ± 0 0.013 ± 0.0088 0.027 ± 0.015 12.33 (SEQ ID (after prime) (after boost) (after prime) (after boost) NO: 48)

Example 8: Construction and Immune Testing of Lentiviral Priming Vectors and Oncolytic Vaccine Vectors Expressing Human Six-Transmembrane Epithelial Antigen of the Prostate Protein

The huSTEAP transgene is full-length wild-type sequence (SEQ ID NO: 11) codon-optimized for expression in human and mouse to give rise to a 341 amino acid protein (SEQ ID NO: 10).

Lentiviruses expressing human Six-Transmembrane Epithelial Antigen of the Prostate protein were made using the pDY.EG.WS lentivirus vector. The huSTEAP transgene was PCR amplified using primers containing the EcoRI restriction site (forward primer ACTGGAATTCATGGAATCACGGAAGGACATC, SEQ ID NO: 22) and the BamHI restriction site (reverse primer ACTGGGATCCTTAAAGCTTCAGCTGGCTACAG, SEQ ID NO: 23). The huSTEAP transgene PCR product was agarose gel purified. The pDY.EG.WS lentivirus vector was cut at the EcoRI/BamHI site to remove eGFP, was agarose gel purified, and was subjected to dephosphorylation using CIAP (Invitrogen Catalogue 18009-019). The cut vector was then subjected to additional agarose gel purification. The huSTEAP transgene PCR product was then ligated into the EcoRI/BamHI cut vector using T4 DNA ligase (Invitrogen). The ligation reaction was subjected to a transformation using competent cells, and plasmid DNA from positive colonies was subjected to mini-prep amplification. The pDY.EG.WS lentivirus vector expressing the modified huSTEAP transgene was then subjected to maxi-prep amplification. The lentivirus expressing huSTEAP transgene were rescued on 293T cells after transfection of 6.4 μg of each of three plasmids: the pDY.EG.WS lentivirus vector expressing the huSTEAP transgene, the packaging pCMV-8.84 plasmid, and the envelope pMD2G plasmid. Virus supernatants were pooled, and filtered through a 0.45 μM filter and centrifuged for 120 minutes at 50,000×g at 16° C. The lentivirus expressing huSTEAP transgene was resuspended in PBS, and stored at −80° C.

Maraba MG1 was engineered to contain human Six-Transmembrane Epithelial Antigen of the Prostate transgene inserted between the G and L viral genes of the MG1 double mutant of Maraba virus (Brun J. et al., (2010) Mol Ther 18:1440-1449). The transgene sequence was codon optimized for expression in mammalian cells. The resulting Maraba MG1 containing the huSTEAP protein is designated as “Maraba-MG1-huSTEAP” or “MG1-huSTEAP”. A modified Maraba MG1 backbone was used to facilitate cloning. A silent mutation was introduced into the L gene of the Maraba MG1 genome backbone to remove one of the Mlul sites. The second Mlul site was replaced with a BsiWI site at the cloning region between G and L. These modifications to the Maraba MG1 genome backbone allowed for a more direct cloning system than that described in the Brun et al. paper as it avoids using the shuttle plasmid pMRB-MG1/pNF. The huSTEAP transgene sequence was ligated into the modified Maraba MG1 genome backbone at its Mlul and BsiWI site (at cloning region between G and L). The Maraba-MG1-huSTEAP was then rescued (as previously described in Brun J. et al., (2010) Mol Ther 18:1440-1449), plaque purified once, and subjected to opti-prep purification. The Maraba-MG1-huSTEAP has a genomic sequence that is the reverse complement and RNA version of SEQ ID NO: 12.

Generally, animals were immunized by administration of the priming vector (lentivirus-huSTEAP+poly I:C as an adjuvant) at day 0 and by administration of 1e9 PFU of the boosting vector (Maraba-MG1-huSTEAP) at day 14. Control animals were prime-boosted with viral vectors encoding GFP instead of the huSTEAP transgene as a control non-immunogenic transgene insertion. Analysis of the prime response was conducted at day 14 and day 19. Each lentivirus-huSTEAP preparation was made with 250 ug poly I:C added as an adjuvant to the priming virus and then split between 5 animals for each virus. Mice were anesthetized with isoflurane and 30 uL of lentivirus-huSTEAP/poly I:C was injected into each hind foot pad. The remaining virus was injected subcutaneously near the left inguinal lymph node. 14 days after prime, blood was collected and analyzed by flow cytometry. Mice were then boosted with 1×10⁹ PFU MG1-huSTEAP intravenously. Five days following the boost, blood was drawn and immune responses were assessed by flow cytometry.

Immune analysis was performed as follows: Blood was collected via retro-orbital bleeding using heparinzied capillary tube and blood was collected into heparin. Red blood cells were then lysed using ACK lysis buffer and the resulting PBMCs were analyzed for immune responses to the tumor antigens. PBMCs were either incubated in the absence of peptide or stimulated with peptides for a total of 5 hours with golgi plug added 1 hour into the stimulation. PBMCs were either incubated in the absence of peptide or stimulated with 2 ug/mL peptides (RSRYKLL) (SEQ ID NO: 49) for a total of 5 hours with golgi plug added 1 hour into the stimulation. Following stimulation the PBMCs were stained for CD4, CD8 and IFNγ and analyzed on FACSCanto and FlowJo. Responding T-cells were detected after intracellular cytokine staining (ICS) for IFN-γ by flow cytometry. Values from unstimulated PBMCs were considered background and subtracted from values obtained from stimulated PBMCs. Data 20 represents mean+/−SEM. In Table 3 it is demonstrated that the huSTEAP peptides were able to stimulate IFN-γ production in CD8 cells indicating the existence of an immune response.

TABLE 3 IMMUNE RESPONSE to huSTEAP PRIME-BOOST Percentage of CD8 T Cells Secreting Interferon (IFN) ^(γ) Immune Group Stimulatory Control Group Lentivirus-huSTEAP Prime Peptide Lentivirus-GFP Prime MG1-huSTEAP Boost Epitope MG1-GFP Boost (N = 5) RSYRYKLL 0.0033 ± 0.0033 0.0033 ± 0.0033 0.008 ± 0.0508 0.0406 ± 0.11 (SEQ ID NO: 49) (after prime) (after boost) (after prime) (after boost)

Example 9: Construction and Immune Testing of Lentiviral Priming Vectors and Oncolytic Vaccine Vectors Expressing Epstein-Barr Nuclear Antigen 1

The EBDNA1 transgene is a partial nucleotide sequence of full-length wild-type EBDNA1 (www.ncbi.nlm.nih.gov/protein/Q1HVF7.1) with the Glycine-Alanine generating repetitive sequence deleted (which separates the protein into amino- and carboxy-terminal domains). This sequence seems to stabilize the protein, preventing proteasomal breakdown, as well as impairing antigen processing and MHC class I-restricted antigen presentation (Levitskaya J et al., (1995) Nature 375:685-688). The truncated EBDNA1 nucleotide sequence (SEQ ID NO: 17) was codon-optimized for expression in human and mouse to give rise to a 238 amino acid protein (SEQ ID NO: 16).

Lentiviruses expressing Epstein-Barr Nuclear Antigen 1 protein were made using the pDY.EG.WS lentivirus vector. The modified EBDNA1 transgene was PCR amplified using primers containing the EcoRI restriction site (forward primer ACTGGAATTCATGCCAGTCGGCCAGGCTG, SEQ ID NO: 24) and the BamHI restriction site (reverse primer ACTGGGATCCTTATTCCTGCCCCTCTTCTCC, SEQ ID NO: 25). The EBDNA1 transgene PCR product was agarose gel purified. The pDY.EG.WS lentivirus vector was cut at the EcoRI and BamHI sites to remove eGFP, was agarose gel purified, and was subjected to dephosphorylation using CIAP (Invitrogen Catalogue 18009-019). The cut vector was then subjected to additional agarose gel purification. The EBDNA1 transgene PCR product was then ligated into the EcoRI/BamHI cut vector using T4 DNA ligase (Invitrogen). The ligation reaction was subjected to a transformation using competent cells, and plasmid DNA from positive colonies was subjected to mini-prep amplification. The pDY.EG.WS lentivirus vector expressing the EBDNA1 transgene was then subjected to maxi-prep amplification. The lentivirus expressing EBDNA1 transgene was rescued on 293T cells after transfection of 6.4 μg of each of three plasmids: the pDY.EG.WS lentivirus vector expressing the EBDNA1 transgene, the packaging pCMV-8.84 plasmid, and the envelope pMD2G plasmid. Virus supernatants were pooled, and filtered through a 0.45 μM filter and centrifuged for 120 minutes at 50,000×g at 16° C. The lentivirus expressing EBDNA1 transgene was resuspended in PBS, and stored at −80° C.

Maraba MG1 was engineered to contain Epstein-Barr Nuclear Antigen 1 transgene inserted between the G and L viral genes of the MG1 double mutant of Maraba virus (Brun J. et al., (2010) Mol Ther 18: 1440-1449). The transgene sequence was codon optimized for expression in mammalian cells. The resulting Maraba MG1 containing the EBVDNA1 protein is designated as “Maraba-MG1-EBVDNA1” or “MG1-EDVDNA1”. A modified Maraba MG1 backbone was used to facilitate cloning. A silent mutation was introduced into the L gene of the Maraba MG1 genome backbone to remove one of the Mlul sites. The second Mlul site was replaced with a BsiWI site at the cloning region between G and L. These modifications to the Maraba MG1 genome backbone allowed for a more direct cloning system than that described in the Brun et al. paper as it avoids using the shuttle plasmid pMRB-MG1/pNF. The EBDNA1 transgene sequence was ligated into the modified Maraba MG1 genome backbone at its Mlul and BsiWI site (at cloning region between G and L). The Maraba-MG1-EBDNA1 transgene was then rescued (as previously described in Brun J. et al., (2010) Mol Ther 18:1440-1449), plaque purified once, and subjected to opti-prep purification.

Generally, animals were immunized by administration of the priming vector (lentivirus-EBDNA1+poly I:C as an adjuvant) at day 0 and by administration of 1e9 PFU of the boosting vector (Maraba-MG1-EBDNA1) at day 14. Control animals were prime-boosted with viral vectors encoding GFP instead of the TM transgene as a control non-immunogenic transgene insertion. Analysis of the prime response was conducted at day 14 and day 19. Each lentivirus-EBDNA1 preparation was made with 250 ug poly I:C added as an adjuvant to the priming virus and then split between 5 animals for each virus. Mice were anesthetized with isoflurane and 30 uL of lentivirus-EBDNA1/poly I:C was injected into each hind foot pad. The remaining virus was injected subcutaneously near the left inguinal lymph node. 14 days after prime, blood was collected and analyzed by flow cytometry. Mice were then boosted with 1×10⁹ PFU MG1-EBVDNA1 intravenously. Five days following the boost, blood was drawn and immune responses were assessed by flow cytometry.

Immune analysis was performed as follows: Blood was collected via retro-orbital bleeding using heparinzied capillary tube and blood was collected into heparin. Red blood cells were then lysed using ACK lysis buffer and the resulting PBMCs were analyzed for immune responses to the tumor antigens. PBMCs were either incubated in the absence of peptide or stimulated with 2 ug/mL peptides (VYGGSKTSL) (SEQ ID NO: 50) for a total of 5 hours with golgi 30 plug added 1 hour into the stimulation. Following stimulation the PBMCs were stained for CD4, CD8 and IFNγ and analyzed on FACSCanto and FlowJo. Responding T-cells were detected after intracellular cytokine staining (ICS) for IFN-γ by flow cytometry. Values from unstimulated PBMCs were considered background and subtracted from values obtained from stimulated PBMCs. Data represents mean+/−SEM. The EBVDNA1 peptides were unable to stimulate IFN-γ production in either CD8 T cells indicating a lack of an immune response, as shown in Table 4.

TABLE 4 IMMUNE RESPONSE to EBVDNA1 PRIME-BOOST Percentage of CD8 T Cells Secreting Interferon (IFN) ^(γ) Immune Group Lentivirus-EBVDNA1 Stimulatory Control Group Prime Peptide Lentivirus-GFP Prime MG1-EBVDNA1 Boost Epitope MG1-GFP Boost (N = 5) VYGGSKTSL 0.055 ± 0.015 0.01 ± 0.0058 0.008 ± 0.0049 0.09 ± 0.05 (SEQ ID (after prime) (after boost) (after prime) (after boost) NO: 50)

Example 10: Effect of Cyclophosphamide on Adenovirus-OV Vaccine Prime-Boost Strategy

Cyclophosphamide (CPA) is a chemotherapeutic agent used to treat various types of cancer. High doses of this drug are required for effective chemotherapy. High doses of CPA are thought to lead to immunosuppression while low doses of the drug can lead to enhanced immune responses against a variety of antigens. Surprisingly, in the heterologous prime-boost strategy of the current disclosure, CPA only results in an increase in immune response when administered prior to the priming of the immune system by the first virus.

In order to generate lung metastases, C57BI/6 mice (8-10 weeks old at study initiation) were injected with 2.5×10⁵ B16-F10 cells (murine melanoma cells expressing the murine DCT antigen) in 200 μl saline water i.v. at day 0. Five days following B16-F10 engraftment, mice received an Ad-hDCT priming vaccine (2×10⁸ pfu in 200 μl PBS i.m.) and this was followed 14 days later by a single i.v. dose of VSV-hDCT (2×10⁹ pfu in 200 μl PBS i.v.) as an oncolytic booster vaccine. Additionally, mice either received vehicle or CPA (1 mg/20 g mouse, i.p.) at day (−1) prior to the prime and/or day 13 prior to the boost. In FIG. 9 it can be seen that CPA given prior to the priming vector significantly increases survival while CPA administered prior to the boosting vector does not extend survival (data not shown).

In the preceding description, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the examples. The above-described examples are intended to be exemplary only. Alterations, modifications and variations can be effected to the particular examples by those of skill in the art without departing from the scope, which is defined solely by the claims appended hereto. 

What is claimed is:
 1. A heterologous prime-boost vaccine for use in inducing an immune response in a mammal comprising: a first virus comprising a nucleic acid capable of expressing an HPV tumour associated antigen, wherein said first virus is capable of generating immunity to said HPV tumour associated antigen; a second virus, said second virus being a Vesiculovirus, said second virus comprising a nucleic acid capable of expressing an HPV tumour associated antigen, wherein said second virus is capable of providing a therapeutic oncolytic effect in said mammal; wherein said first virus is immunologically distinct and physically isolated from said second virus; and wherein the amino acid sequence of the HPV tumour associated antigen comprises the amino acid sequence of SEQ ID NO.
 7. 2. The heterologous prime-boost vaccine of claim 1, wherein said second virus is Maraba MG1.
 3. The heterologous prime-boost vaccine of claim 2, wherein the amino acid sequence of the HPV tumour associated antigen consists of the amino acid sequence of SEQ ID NO:
 7. 4. The heterologous prime-boost vaccine of claim 3, wherein the amino acid sequence of the HPV tumour associated antigen is encoded by the nucleotide sequence of SEQ ID NO:
 8. 5. The heterologous prime-boost vaccine of claim 4, wherein the Maraba MG1 genome includes a reverse complement and RNA version of the nucleotide sequence of SEQ ID NO:
 9. 6. The heterologous prime-boost vaccine of claim 1, wherein the amino acid sequence of the HPV tumour associated antigen consists of the amino acid sequence of SEQ ID NO:
 7. 7. The heterologous prime-boost vaccine of claim 6, wherein the amino acid sequence of the HPV tumour associated antigen is encoded by the nucleotide sequence of SEQ ID NO:
 8. 8. The heterologous prime-boost vaccine of claim 1, wherein said first and second viruses express the same HPV tumour associated antigen.
 9. An HPV antigenic protein comprising an amino acid sequence that is at least 80% identical to the amino acid sequence of SEQ ID NO:
 7. 10. The antigenic protein of claim 9, wherein said antigenic protein comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:
 7. 11. An isolated viral particle having a nucleic acid comprising a nucleotide sequence capable of encoding the antigenic protein of claim
 9. 12. The isolated viral particle of claim 11, wherein the isolated viral particle is a Vesiculovirus particle.
 13. The isolated viral particle of claim 12, wherein the isolated Vesiculovirus particle is a Maraba MG1 viral particle.
 14. The isolated viral particle of claim 11, wherein said nucleotide sequence encodes a protein comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:7.
 15. The isolated viral particle of claim 13, wherein the genome of said viral particle comprises a reverse complement and RNA version of the nucleotide sequence of SEQ ID NO:
 9. 16. The isolated viral particle of claim 15, wherein said viral particle capable of expressing an HPV antigen having the amino acid sequence of SEQ ID NO:
 7. 17. The heterologous prime-boost vaccine of claim 1, wherein said first virus is formulated for intramuscular administration.
 18. The heterologous prime-boost vaccine of claim 2, wherein said second virus is formulated for intravenous administration.
 19. The heterologous prime-boost vaccine of claim 18, wherein said first virus is formulated for intramuscular administration.
 20. The antigenic protein of claim 10, wherein said antigenic protein comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO:
 7. 21. The antigenic protein of claim 20, wherein said antigenic protein comprises the amino acid sequence of SEQ ID NO:
 7. 22. The antigenic protein of claim 21, wherein the amino acid sequence of said antigenic protein consists of the amino acid sequence of SEQ ID NO:
 7. 23. The antigenic protein of claim 21, wherein said antigenic protein is encoded by the nucleotide sequence of SEQ ID NO:
 8. 24. The isolated viral particle of claim 14, wherein said nucleotide sequence encodes a protein comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO:7.
 25. The isolated viral particle of claim 24, wherein said nucleotide sequence encodes a protein comprising the amino acid sequence of SEQ ID NO:
 7. 26. The isolated viral particle of claim 25, wherein said nucleotide sequence encodes a protein whose amino acid sequence consists of the amino acid sequence of SEQ ID NO:
 7. 27. The isolated viral particle of claim 25, wherein said nucleotide sequence comprises the nucleotide sequence of SEQ ID NO:
 8. 